Gordon Brown said today that British ratification of the EU's Lisbon treaty will not take place until after a judgment on a high court case brought by a millionaire Eurosceptic.

High court judge Lord Justice Richards said he was surprised that the government was going ahead with ratification before he had delivered his ruling on Stuart Wheeler's bid to force a referendum. A decision in the case is expected next week.

But the prime minister told a Brussels press conference that the court ruling fitted the government's ratification timetable, which could take weeks or even months to complete.

"The judgment is expected in the next week and, of course, that fits in with our timetable that we have to go through all the processes before ratification, so ratification will not take place until after a judgment from the court," Brown told reporters.

Earlier Richards said he was "very surprised" to receive a letter from lawyers for the government yesterday saying that they were pressing ahead with ratification.

After the EU (Amendment) Act gained royal assent yesterday, lawyers for the Treasury wrote to the high court to say: "The government is now proceeding to ratify the Treaty of Lisbon."

In a direction released today, Richards said: "The court is very surprised that the government apparently proposes to ratify while the claimant's challenge to the decision not to hold a referendum on ratification is before the court. "The court expects judgment to be handed down next week. The defendants are invited to stay their hand voluntarily until judgment."

Richards also said in his direction that, if the government declined to offer assurances to hold back on ratification until after his ruling, he would personally hear any application from Wheeler for an injunction.

The Eurosceptic millionaire has sought judicial review of the decision to ratify the treaty without a referendum. He argues that he had a "legitimate expectation" there would be a public vote after one was promised by Labour on the constitutional treaty, the forerunner of the Lisbon treaty, which many argue is practically the same thing.

Wheeler, who described the government lawyers' letter as "an insult to the court and to the people of Britain", welcomed the judge's direction.

"Lord Justice Richards is evidently as surprised as I am by the government's determination to ratify this treaty at this point in time," he said. "The government cannot simply ignore the impending judgment and Lord Justice Richards has made it clear he will not allow them to do so.

"The fact that the judge is happy to hear an application from me at any time during the weekend shows how seriously he is taking this."

Wheeler later said he was "very likely" to take his case to the Court of Appeal if the high court ruled against him next week.

He told BBC Radio 4's World at One: "I hope to win. If I do lose, I will have to see how strong the judgment is, consult my QC and take my decision at that point.

"I certainly have a legal right, as one does in any case, to appeal to the Court of Appeal."

Wheeler said he believed the Lisbon treaty was anyway "dead" as a result of its rejection in last week's referendum in Ireland.

The spreadbetting tycoon, who has made large donations to the Conservative party in the past, said he would like to see leader David Cameron demand "substantial changes" to the way the EU runs, if he won power, with British withdrawal as the "ultimate resort" in any negotiations.

The judge's comments were quickly seized upon by Mark Francois, the shadow junior foreign minister, who said the ruling was an embarrassment for the government.

He described Wheeler's court bid as a "brave" move, adding: "Whatever the outcome the government should not be pressing for ratification because it does not have the consent of the British people."

Although the UK in effect became the 19th EU state to ratify the treaty when the EU Amendment Act received royal assent yesterday, the process is not technically completed until the "instruments of ratification" are deposited in Rome.

The Foreign Office has until the end of December to complete this stage, although officials have said they expect to do so by the end of next month.

The treaty will not come into force until all 27 EU member countries have done the same.